Prior to the present invention, as shown by Kookootsedes et al., U.S. Pat. No. 3,445,420, one component organopolysiloxane compositions were based on a platinum catalyzed silicon hydride-silicon vinyl addition reaction which generally utilized an inhibitor for the platinum catalyst. The purpose of the inhibitor was to slow down the hydrosilation reaction to increase the work life of the one component organopolysiloxane mixture at low or room temperature. The organopolysiloxane mixtures were generally composed of a base polymer consisting of a polydiorganosiloxane having chemically combined methylvinylsiloxy units which was used with a cross-linking siliconhydride-siloxane having chemically combined organosilicon hydride siloxy units. Additional inhibited one package silicon hydride-silicon vinyl one package platinum addition curable organopolysiloxane compositions are shown by Berger et al., U.S. Pat. No. 3,882,083, utilizing an ethyleneically unsaturated isocyanurate as an inhibitor, and U.S. Pat. Nos. 4,472,562 and 4,472,563 employing acetylenic unsaturated inhibitors.
Although the inhibitors utilized in the aforementioned one package platinum catalyzed organopolysiloxane compositions generally imparted improved shelf life stability to the resulting heat curable organopolysiloxane composition, improvements in shelf life stability at ambient temperatures with increased activity at elevated temperatures, such as 150.degree. C., are constantly being sought. In addition, it would be desirable to utilize one package organopolysiloxane compositions having an effective amount of a platinum cure catalyst which does not require the use of an organic or inorganic inhibitor.
The present invention is based on my discovery that certain cyclometallized platinum phosphite complexes, as defined hereinafter, have been found to provide significantly improved inhibitor-free, one package organopolysiloxane compositions comprising organopolysiloxane having chemically combined monovalent olefinically unsaturated organic radicals attached to silicon by carbon-silicon linkages which is utilized in combination with organopolysiloxane having chemically combined hydrogen atoms attached to silicon by silicon-hydride linkages. In addition, the shelf life of the one package organopolysiloxane composition at ambient temperatures utilizing such cyclometallized platinum phosphite catalyst have been found to be superior to the inhibited platinum catalyzed one package organopolysiloxane compositions of the prior art.